My lilac starts green and robust, then its leaves turn brown and it looks dead. It looks good again after two weeks. This happens three or four times in summer. What’s up?” Birds & Blooms reader Robert Snyder
Horticulturist Melinda Myers: Drought may cause certain symptoms. Examine lilac leaves throughout the season, track rainfall and irrigation, and discover if they are related.
Bacteria-caused lilac blight can curl leaves. Leaves and young shoots may have brown spots. The sole control is pruning infected branches below the affected part. Between cuts, sanitise tools with alcohol or spray.
Curled, green, spot-free leaves may indicate a root issue caused by too much or too little water. Water deeply and less often to promote deep roots.
Melinda: No plant is deer-proof. Deer browse and shred plants, creating ragged tissue. Rabbit teeth are sharp and cut cleanly like bypass pruners. They may only eat leaves within 3 feet of the ground. Squirrels can tear bark and foliage.
Scare methods may work to deter some animals, but most urban and suburban species are habituated to people. Consider using a rain- and snow-resistant repellant like Plantskydd to reduce deer, squirrels, and rabbits. Applicants will need to apply less often.